Yes, certainly you must exercise.
The benefits of exercise are now proven beyond doubt - there are so many studies that confirm this.
The most important benefit is of course health - cardiac health, bone, muscle, and all around from cancer prevention to greater testosterone levels.
Besides this, exercise also keeps you happy, makes your sex life better, improves your looks (because of increased skin circulation), keeps you looking and feeling younger.
Irrespective of your diet, exericse is extremely important.
Jog for at least 30 minutes 5 days a week, that is sufficient. Adding weight exercises will be a further benefit.
Read up here for an article on this:http://www.mayoclinic.com/health/exercise/HQ01676
Take care - exercise is vitally important - dont neglect
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Dr. P.Jyoti, MD.